Special Weather Statement, NWS Tulsa, OK

Area Forecast Discussion
National Weather Service Tulsa OK
642 PM CDT Fri Apr 28 2017

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Flight conditions will deteriorate as showers and thunderstorms
become numerous overnight and continue through the day Saturday.

&&

.PREV DISCUSSION... /Issued 319 PM CDT Fri Apr 28 2017/

DISCUSSION...
A significant flood/flash flood event is gradually evolving across
the region...although confidence remains low concerning the axis
of heaviest rainfall as wide model spread persists with the 12z
runs. Severe weather will be an issue as well...especially by late
evening/overnight and again Saturday afternoon.

Warm front that was analyzed across northern TX earlier this
morning has lifted into far southern OK...with dewpoints pooling
around 65-70F along/just north of the boundary. A strong cap noted
on OUN/FWD soundings should prohibit convection for the rest of
the day and well into the evening...with storms likely holding off
until after 9-10 pm as the low-level jet strengthens. Great areal
coverage of storms will be north of the warm front which should be
lifting farther north into southeast OK...with highest rainfall
total generally along and north of I-40. The main severe threat
will come from large hail given the overall elevated nature of the
convection...although any storms that remain near the warm front
and rooted closer to the boundary layer may become supercellular.

Going into Saturday...deep/moist southwesterly upper flow in
advancing of approaching upper level will nearly parallel the
synoptic frontal system. With PW values running near 2 inches
(above the 90th percentile for this time of year)...expect periods
of very heavy rainfall across the region. 12z models continue to
show significant differences with the heaviest rain axis...with
the NAM/GFS farther north while the ECMWF has remained consistent
with its previous run keeping the axis roughly from southeast OK
into northwest AR. Severe weather will be possible as well late
in the day and into the evening...especially across southeast OK
as the triple point scoots east across this area.

We plan on blending both the WPC precip forecast along with the
latest ECMWF...which results in a large swath of 4-6 inch rains
from southeast OK-northwest AR...with local amounts over 8 inches.
Given the wet antecedent conditions (especially in northwest AR)
this will result in significant flooding...main stem river
flooding and potential flash flooding.

Please note...this is an evolving system and the axis of heavy
will likely be fine tuned...so stay aware of the latest updates
over the next 24-36 hours.

The upper low will lift northeast of the area on Sunday...with
some lingering light wraparound showers and breezy/cool
conditions.

Quiet weather expected into early next week...with the next chance
of showers/storms coming Tuesday night into Wednesday as a
shortwave dives southeast into the Plains.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flash Flood Watch through Sunday morning for OKZ049-053-057-058-
     060>076.

AR...Flash Flood Watch through Sunday morning for ARZ001-002-010-011-
     019-020-029.

&&

AVIATION...05

Hazardous Weather Outlook
National Weather Service Tulsa OK
535 PM CDT Fri Apr 28 2017

ARZ001-002-010-011-019-020-029-OKZ049-053>076-291045-
Adair OK-Benton AR-Carroll AR-Cherokee OK-Choctaw OK-Craig OK-
Crawford AR-Creek OK-Delaware OK-Franklin AR-Haskell OK-Latimer OK-
Le Flore OK-Madison AR-Mayes OK-McIntosh OK-Muskogee OK-Nowata OK-
Okfuskee OK-Okmulgee OK-Osage OK-Ottawa OK-Pawnee OK-Pittsburg OK-
Pushmataha OK-Rogers OK-Sebastian AR-Sequoyah OK-Tulsa OK-Wagoner OK-
Washington OK-Washington AR-
535 PM CDT Fri Apr 28 2017

...SIGNIFICANT FLOODING AND SEVERE RISK THRU THE WEEKEND...

This Outlook is for Northwest and West Central Arkansas as well as
much of Eastern Oklahoma.

.DAY ONE...This evening and Tonight.
TORNADO.
	RISK...Limited.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...After 8 pm.

	Area OF GREATER RISK...Mainly north of a McAlester to Fort Smith
						   line and along and south of Interstate 44.

SEVERE THUNDERSTORM.
	RISK...Significant.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...After 8 pm.

	AREA AT GREATEST RISK...Mainly north of a McAlester to Fort Smith
						   line and along and south of Interstate 44.

FLASH FLOOD.
	RISK...Elevated.
	AREA...Northeast Oklahoma and Northwest Arkansas.
	ONSET...After 8 pm.

HEAVY RAIN.
	RISK...Elevated.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...After 8 pm.

DISCUSSION...
Severe storm chances along with potential flash flooding will
increase this evening and overnight tonight across Eastern
Oklahoma and Northwest Arkansas. Very large hail to baseball size,
damaging winds to 70 mph, and an isolated tornado are possible.

Clusters of thunderstorms continuing to develop over the Oklahoma
and Texas Panhandles will continue to push eastward and move into
Eastern Oklahoma and Northwest Arkansas late this evening and
overnight. At the same time...additional thunderstorms are
forecast to develop this evening and tonight along and north of a
warm frontal boundary lifting north across Southeast Oklahoma and
Western Arkansas. All modes of severe weather will be possible
with this activity through into the overnight hours and transition
to more of a large hail and damaging wind threat late tonight
across the region.

Also through tonight...multiple rounds of heavy rainfall are
expected to develop across Eastern Oklahoma and Northwest Arkansas
as the frontal boundary becomes nearly stationary over the region.
This will increase the potential for flash flooding with the
greater potential over Northeast Oklahoma into Northwest Arkansas.
A flash flood watch is in effect starting this evening and
continuing into Sunday morning.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Activation of the Regional Spotter Network Expected.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.
SATURDAY...Severe Thunderstorm Potential...Heavy Rain Potential.
SUNDAY...No Hazards.
MONDAY...High Wind Potential.
TUESDAY and WEDNESDAY...Thunderstorm Potential.
THURSDAY...No Hazards.

EXTENDED DISCUSSION...
Multiple rounds of thunderstorms will continue to impact the region
Saturday and Saturday night as a powerful upper level storm system
develops to our west and interacts with a frontal boundary draped
over the region. Storm total rainfall in the 4 to 7 inch range is
expected, with locally heavier amounts likely across much of northeast
and east central Oklahoma into Northwest Arkansas thru Sunday.
This heavy rainfall could lead to life-threatening flash flooding
and significant flooding of area rivers and lakes. Locations
downstream from dams could see significant flooding as water is
released from the flooded lakes.

The quasi-stationary frontal boundary and approaching upper system
will continue to be the focus for storms with severe potential
during the afternoon and evening hours Saturday. The severe
weather threat...and heavy rainfall threat will will come to an
end from west to east as a cold front sweeps across the region
late Saturday night into Sunday morning.

Towards the middle of next week...another storm system will bring
the potential for more storms to the region. This system is expected
to push through too quickly to bring significant rainfall. Organized
severe weather is not expected either.

EMERGENCY MANAGEMENT PLANNING STATEMENT...
This is an evolving system and the axis of heavy rainfall will
likely continue to be fine tuned. Continue to follow the latest
updates and forecasts over the next 24 to 36 hours regarding the
expected hazardous weather that will affect much of the area this
weekend.

weather.gov/tulsa Contains additional information.

Special Weather Statement
National Weather Service Tulsa OK
937 PM CDT FRI APR 28 2017

ARZ002-011-290300-
Carroll AR-Madison AR-
937 PM CDT FRI APR 28 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MADISON AND EASTERN
CARROLL COUNTIES UNTIL 1000 PM CDT...

At 937 PM CDT, a strong thunderstorm was located 4 miles northeast of
Aurora, moving northeast at 50 mph.

Nickel size hail will be possible with this storm.

Locations in or near the path include...
Huntsville...                     Green Forest...
Carrollton...                     Rudd...
Kingston...                       Marble...
Aurora...                         Osage...
Rule...                           Alpena...
Dryfork...                        Cabanal...
Harmony...                        Metalton...
Connor...                         Coin...
Alabam...                         Delmar...
Denver...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3612 9337 3612 9348 3608 9348 3608 9345
      3607 9345 3593 9364 3606 9380 3647 9339
      3639 9329 3617 9330
TIME...MOT...LOC 0237Z 223DEG 43KT 3606 9366